Uplink transmission power control method and apparatus

ABSTRACT

A method and an apparatus for controlling uplink transmission power in a wireless communication system are provided. The apparatus receives transmit power command (TPC) monitoring information for receiving a plurality of TPCs for adjusting uplink transmission power for a plurality of serving cells. The apparatus obtains the plurality of TPCs by monitoring a downlink control channel on the basis of the TPC monitoring information.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Phase of PCT International ApplicationNo. PCT/KR2015/013685, filed on Dec. 14, 2015, which claims priorityunder 35 U.S.C. 119(e) to U.S. Provisional Application No. 62/091,631,filed on Dec. 15, 2014, all of which are hereby expressly incorporatedby reference into the present application.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to wireless communication, and moreparticularly, to a method for controlling uplink transmission power in awireless communication system and an apparatus using the same.

Related Art

With the development of mobile technology, data traffic usage is rapidlyincreasing. Standardization and technical development in various fieldsare underway to quickly process a great amount of data traffic usinglimited radio resources. Representative technologies are 3D beamforming,massive multiple-input multiple-output (MIMO), a heterogeneous network,and a small cell.

A small cell is a technology for increasing traffic capacity and datarate. Generally, a small cell is deployed as a hotspot in macrocellcoverage. A backhaul between a small cell and a macrocell may be idealor non-ideal. An ideal backhaul is assumed in intra-site carrieraggregation (CA) or coordinated multi-point (CoMP) technology. Dualconnectivity is referred to as inter-site CA, in which a non-idealbackhaul is assumed.

A method for controlling uplink transmission power with a plurality ofcells set is proposed.

SUMMARY OF THE INVENTION

The present invention provides a method for controlling uplinktransmission power in a wireless communication system and an apparatususing the same.

In an aspect, a method for controlling uplink transmission power in awireless communication system is provided. The method includesreceiving, by a wireless device, transmit power command (TPC) monitoringinformation for receiving a plurality of TPCs to adjust an uplinktransmission power for a plurality of serving cell, receiving, by thewireless device, a TPC payload by monitoring a downlink control channelbased on the TPC monitoring information, acquiring a plurality of TPCswithin the TPC payload, and applying the plurality of TPCs to the uplinktransmission power for each of the plurality of serving cells.

The TPC monitoring information may comprise a TPC identifier masked witha cyclic redundancy check (CRC) of the downlink control channel andinformation on a plurality of TPC indexes indicating the plurality ofTPCs within the TPC payload.

The TPC monitoring information may comprise information on a size of theTPC payload.

In another aspect, an apparatus for controlling uplink transmissionpower in a wireless communication system includes a transceiverconfigured to transmit and receive a radio signal, and a processorconnected to the transceiver. The processor is configured to instructthe transceiver to receive transmit power command (TPC) monitoringinformation for receiving a plurality of TPCs to adjust an uplinktransmission power for a plurality of serving cell, instruct thetransceiver to receive a TPC payload by monitoring a downlink controlchannel based on the TPC monitoring information, instruct thetransceiver to acquire a plurality of TPCs within the TPC payload, andinstruct the transceiver to apply the plurality of TPCs to the uplinktransmission power for each of the plurality of serving cells.

When a plurality of uplink channels is transmitted from a plurality ofserving cells, it is possible to adjust uplink transmission power foreach uplink channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows uplink (UL) power control in existing 3GPP LTE.

FIG. 2 shows an example of DCI format 3/3A in 3GPP LTE.

FIG. 3 shows various examples of scenarios of configuring a plurality ofcells.

FIG. 4 is a flowchart illustrating UL transmission power controlaccording to one embodiment of the present invention.

FIG. 5 shows UL transmission power control according to anotherembodiment of the present invention.

FIG. 6 is a block diagram illustrating a wireless communication systemaccording to one embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A wireless device may be fixed or mobile, and a user equipment (UE) maybe referred to as another term, such as a mobile station (MS), a mobileterminal (MT), a user terminal (UT), a subscriber station (SS), apersonal digital assistant (PDA), a wireless modem, a handheld device,and the like. Alternatively, the wireless device may be a devicesupporting only data communication, such as a machine-type communication(MTC) device.

Abase station (BS) generally refers to a fixed station that communicateswith a wireless device and may be referred to as another term, such asan evolved NodeB (eNB), a base transceiver system (BTS), an access point(AP), and the like.

In the following description, the present invention is applied on thebasis of 3rd Generation Partnership Project (3GPP) Long Term Evolution(LTE) based on the 3GPP Technical Specifications (TSs). However, this ismerely an example, and the present invention may be applied to variouswireless communication networks.

In 3GPP LTE, scheduling is performed per subframe. For example, onesubframe has a length of 1 ms, which is defined as a transmission timeinterval (TTI). A radio frame includes 10 subframes, and one subframemay include two consecutive slots. A subframe may include a plurality oforthogonal frequency division multiplexing (OFDM) symbols. As 3GPP LTEuses orthogonal frequency division multiple access (OFDMA) in a downlink(DL), an OFDM symbol is provided merely to express one symbol period ina time domain, and the present invention is not limited by a multipleaccess mode or term. For example, an OFDM symbol may be referred to asanother term, such as a single carrier-frequency division multipleaccess (SC-FDMA) symbol, a symbol interval, and the like. According to3GPP LTE, one subframe includes 14 OFDM symbols in a normal cyclicprefix (CP), and one subframe includes 12 OFDM symbols in an extendedCP.

Physical channels in 3GPP LTE may be divided into downlink (DL) physicalchannels and uplink (UL) physical channels. The DL physical channelsinclude a physical downlink control channel (PDCCH), a physical controlformat indicator channel (PCFICH), a physical hybrid-ARQ indicatorchannel (PHICH), and a physical downlink shared channel (PDSCH). The ULphysical channels include a physical uplink control channel (PUCCH) anda physical uplink shared channel (PUSCH).

A PCFICH transmitted in the first OFDM symbol of a subframe carries acontrol format indicator (CIF) on the number of OFDM symbols used fortransmission of control channels in the subframe (i.e., the size of acontrol region). A wireless device first receives the CIF on the PCFICHand then monitors a PDCCH.

A PHICH carries a positive-acknowledgement(ACK)/negative-acknowledgement (NACK) signal for an uplink hybridautomatic repeat request (HARD). The ACK/NACK signal for uplink (UL)data on a PUSCH transmitted by the wireless device is sent on the PHICH.

Control information transmitted through a PDCCH is referred to asdownlink control information (DCI). The DCI may include PDSCH resourceallocation (which is also referred to as a downlink (DL) grant), PUSCHresource allocation (which is also referred to as an uplink (UL) grant),a set of transmission power control commands for individual UEs in a UEgroup, and/or activation of Voice over Internet Protocol (VoIP).

Blind decoding is used for detecting a PDCCH. Blind decoding is a schemein which a wireless device demasks a cyclic redundancy check (CRC) of areceived PDCCH (which is referred to as a candidate PDCCH) with adesired identifier and checks a CRC error to identify whether the PDCCHis a control channel for the wireless device. ABS determines a PDCCHformat according to DCI to be sent to a wireless device and adds a CRCto the DCI. Then, the BS masks the CRC with a unique identifier (whichis referred to as a radio network temporary identifier (RNTI)) dependingon the owner or purpose of the PDCCH.

A PUCCH carries uplink control information (UCI) and supports multipleformats. A PUCCH having a different number of bits per subframe may beused depending on a modulation scheme subordinate to a PUCCH format.PUCCH format 1 is used for transmission of a scheduling request (SR);PUCCH format 1a/1b is used for transmission of a CQI; and PUCCH format2a/2b is used for simultaneous transmission of CQI and an ACK/NACKsignal.

FIG. 1 shows UL power control in existing 3GPP LTE.

ABS transmits information on a transmit power command (TPC) 10 to awireless device. The TPC 10 is information sent by the BS to adjust ULtransmission power and is received on a PDCCH. First, the TPC 10 may betransmitted via DCI along with scheduling information for DLtransmission or UL transmission. Second, the TPC 10 may be transmittedvia DCI sending UL transmission power (which is referred to as DCIformat 3/3A). A 1-bit TPC indicates DCI format 3A, while a 2-bit TPCindicates DCI format 3.

The wireless device determines UL transmission power based on the TPC 10and transmits a UL channel 20 based on the UL transmission power.

Referring to Section 5 in 3GPP TS 36.213 V10.12.0 (2014 March),transmission power PPUSCH(i) for PUSCH transmission in subframe i isdefined as below:

                                     [Equation  1]${P_{PUSCH}(i)} = {\min\begin{Bmatrix}{{P_{CMAX}(i)},} \\{{10\;{\log_{10}\left( {M_{PUSCH}(i)} \right)}} + {P_{O\_ PUSCH}(j)} + {{\alpha(j)}{PL}_{c}} + {\Delta_{TF}(i)} + {f(i)}}\end{Bmatrix}}$

where

P_(CMAX) is a maximum transmission power configured for subframe i,

M_(PUSCH)(i) is a PUSCH resource allocation bandwidth for subframe i,

P_(O) _(_) _(PUSCH)(j) is a parameter given from an upper layer,

α(j) is a parameter given to an upper layer,

PLc is a DL path loss estimate calculated by a wireless device,

Δ_(TF)(i) is a wireless device-specific parameter, and

f(i) is a specified value acquired from a TPC.

A transmission power P_(PUCCH)(i) for PUCCH transmission in subframe iis defined as below:

                                     [Equation  2]${P_{PUCCH}(i)} = {\min\left\{ \begin{matrix}{{P_{CMAX}(i)},} \\{P_{0{\_ PUCCH}} + {PL}_{c} + {h\left( {n_{CQI},n_{HARQ},n_{SR}} \right)} + {\Delta_{F\_ PUCCH}(F)} + {\Delta_{TxD}(F)} + {g(i)}}\end{matrix} \right\}}$

where

P_(CMAX) is a maximum transmission power configured for subframe i,

PLc is a DL path loss estimate calculated by a wireless device,

P_(O) _(_) _(PUCCH) is a parameter given by a BS,

h(n_(CQI), n_(HARQ), n_(SR)) is a value dependent to a PUCCH format,

Δ_(F) _(_) _(PUCCH)(F) is a parameter given by an upper layer,

Δ_(TxD)(F) is a value set when a PUCCH is transmitted through multipleantennas, and

g(i) is a specified value acquired from a TPC.

FIG. 2 shows an example of DCI format 3/3A in 3GPP LTE.

TPC(n) is an nth TPC value, and n is a TPC index. N TPC values form apayload, and a CRC is added thereto. The CRC is masked with a TPC-RNTIto identify DCI format 3/3A having a TPC.

A wireless device demasks the TCP-RNTI to monitor a PDCCH per subframe.When DCI is received a PDCCH without a CRC error, the wireless deviceapplies a TPC corresponding to a pre-assigned TPC index to ULtransmission power.

Hereinafter, a multi-cell environment is described.

In a carrier aggregation (CA) environment or dual connectivityenvironment, a wireless device may be served by a plurality of servingcells. Each serving cell may be defined by a downlink (DL) componentcarrier (CC) or a pair of a DL CC and a UL CC.

The serving cells may be divided into a primary cell and a second armycell. A primary cell is a cell that operates at a primary frequency,performs an initial connection establishment process, starts aconnection reestablishment process, or is designated as a primary cellin a handover process. A secondary cell operates at a secondaryfrequency, may be configured after a radio resource control (RRC)connection is established, and may be used to provide an additionalradio resource. At least one primary cell is always configured, and asecondary cell may be added/modified/released by an upper-layersignaling (for example, an RRC message). The primary cell may have afixed cell index (CI). For example, the lowest CI may be assigned to theprimary cell. Hereinafter, the primary cell has a CI of 0, and secondarycells are sequentially assigned CIs from 1.

FIG. 3 shows various examples of scenarios of configuring a plurality ofcells.

A first BS 110 is a macro BS having large coverage, and second and thirdBSs 120 and 130 are small BSs having relatively small coverage. A cellmanaged by the macro BSs 110 is a macro cell, and cells managed by thesmall cells 120 and 130 are small cells. Each of the BSs 110, 120, and130 may manage one or more cells.

In scenario 1, the macro BS 110 and the small BSs 120 and 130communicate with a wireless device 140 using the frequency band. Inscenario 2, the macro BS 110 and the small BSs 120 and 130 communicatewith the wireless device 140 using different frequency band. In scenario2, the small BS 120 is located out of the coverage of the macro BS 110and communicates with the wireless device 140 using a frequency band thesame as or different from that for the macro BS 110.

In a dual connectivity situation, a master cell group (MCG) and asecondary cell group (SCG) may be configured for a wireless device forwhich a plurality of cells is configured. The MCG is a serving cellgroup having a primary cell (PCell) and zero or more secondary cells(SCells). The MCG may be served by the macro BS 110, and the SCG may beserved by one or more small BSs 120 and 130. The SCG is a secondary cellgroup having a primary secondary cell (PSCell) and zero or moresecondary cells. An MCG cell is a cell belonging to the MCG, and an SCGcell is a cell belonging to the SCG. The PSCell is a secondary cell towhich the wireless device performs random access and to which an uplinkcontrol channel (for example, a PUCCH) is transmitted.

To prevent a concentration of PUCCH traffic in a specific cell, anetwork may support PUCCH offloading in a CA situation although notsupporting dual connectivity. The network may divide a plurality ofserving cells configured for a wireless device into a plurality of cellgroups and may configure at least one cell in each cell group totransmit a PUCCH.

Hereinafter, a cell group including a PCell is defined as a first cellgroup, and a cell group including at least one secondary cell is definedas a second cell group. A cell capable of PUCCH transmission in thefirst cell group is defined as a first PUCCH cell, and a cell capable ofPUCCH transmission in the second cell group is defined as a second PUCCHcell. The first PUCCH cell and the second PUCCH cell may independentlytransmit a UL channel. The first PUCCH cell may be the PCell. The secondPUCCH cell may be a PSCell or SCell. Hereinafter, the first PUCCH cellmay be designated by a PCell, and the second PUCCH cell may bedesignated by a PPCell. The PCell may send a message to designate aPPCell among cells in the second cell group.

As described above, PUCCH transmission in only one cell is consideredfor existing UL transmission power. Thus, it is proposed how to controlUL transmission power for two PUCCHs when the two PUCCHs are transmittedin the PCell and the PPCell.

Although the following description is made on controlling ULtransmission power for two PUCCHs transmitted in two cells, a personskilled in the art may readily apply this description to controlling ULtransmission power for a plurality of PUCCHs transmitted in a pluralityof cells.

First, the PCell and the PPCell are given DCI format 3/3A illustrated inFIG. 2, which may be used for control of PUCCH transmission power forthe cells. For example, suppose that the PCell receives first DCI format3 and the PPCell receives second DCI format 3. First DCI format 3 may bemonitored based on a first TPC-RNTI, and second DCI format 3 may bemonitored based on a second TPC-RNTI. The wireless device may apply aTPC of first DCI format 3 to transmission power for a first PUCCHtransmitted in the PCell and may apply a TPC of second DCI format 3 totransmission power for a second PUCCH transmitted in the PPCell. In thismanner, the wireless device has an advantageous of utilizing theexisting DCI format 3/3A structure. However, the wireless deviceperforms separate blind decoding on the two DCI formats, thus increasingadditional monitoring loads.

FIG. 4 is a flowchart illustrating UL transmission power controlaccording to one embodiment of the present invention.

A wireless device receives TPC monitoring information (S410). The TPCmonitoring information is information used for the wireless device tomonitor a DL control channel having a TPC over a plurality of cells. TheTPC monitoring information may be received through an RRC message, amedium access control (MAC) message, or DCI.

The following table illustrates examples of elements included in the TPCmonitoring information. Illustrated terms are provided only forillustrative purposes, and not all elements are essential.

TABLE 1 Term Description MTPC-RNTI Identifier masked with CRC of DCIincluding TPC over a plurality of cells First TPC-index Index of TPCapplied to PUCCH transmission in first PUCCH cell Second TPC-index Indexof TPC applied to PUCCH transmission in second PUCCH cell TPC payloadsize Payload size of DCI and/or information on total number of TPCs inDCI

The wireless device monitors a PDCCH based on the TPC monitoringinformation to receive a TPC (S420). The PDCCH may be monitored in acommon search space of a corresponding subframe in a PCell.

The TPC monitoring information may include information on the type orlocation of a search space in which the PDCCH is to be monitored. TheTPC monitoring information may include information on a cell in whichthe PDCCH is to be monitored.

The wireless device identifies a CRC of the PDCCH using an MTPC-RNTI inthe common search space. When no CRC error is detected, the wirelessdevice acquires a TPC payload from the PDCCH. The wireless device mayacquire a first TPC corresponding to a first TPC-index and a second TPCcorresponding to a second TPC-index from the TPC payload. The first TPCand the second TPC may have the same number of bits (1 bit or 2 bit).Alternatively, the first TPC and the second TPC may have differentnumbers of bits.

The wireless device applies the first TPC to transmission power for afirst PUCCH and applies the second TPC to transmission power for asecond PUCCH (S430). The transmission powers for the respective PUCCHsmay be calculated by Equation 2. The first PUCCH may be transmitted inthe PCell, and the second PUCCH may be transmitted in a PPCell. Thefirst PUCCH and the second PUCCH may be transmitted in the same subframeor in different subframes.

ABS transmits TCP information to be applied to a PUCCH transmitted in aplurality of PUCCH cells to each wireless device on a PDCCH. The payloadsize of the TPC information may be defined according to the payload sizeof existing DCI format 3/3A in order to reduce the number of PDCCH blinddetection times.

Meanwhile, a TPC-RNTI may be assigned per PUCCH cell. The BS may set aseparate TPC-RNTI and a separate TPC-index for each PUCCH cell. Thewireless device may receive a TPC over each different cell on eachdifferent PDCCH.

Alternatively, a common TPC-index may be applied to two or more PUCCHcells, and a separate TPC RNTI may be assigned per PUCCH cell.

The same TPC-RNTI and the same TPC-index may be applied to all PUCCHcells.

FIG. 5 shows UL transmission power control according to anotherembodiment of the present invention, which is UL power control using DLscheduling DCI.

DCI 510 received in a PCell includes information on DL scheduling for aPDSCH 520 and a TPC. A wireless transmits an HARQ ACK/NACK for the PDSCH520 on a PUCCH 530 in a PPCell.

The DCI 510 may include a TPC over the PUCCH 530. When the ACK/NACKfeedback on the PDSCH 520 of the PCell is transmitted in the PPCell, theTPC in the DCI 510 scheduling the PDSCH 520 is applied to the PUCCH 530for the ACK/NACK feedback.

The DIC 510 is transmitted not only in the PCell but may be transmittedin an SCell in which a PDSCH or PDCCH is transmitted.

Hereinafter, an initial power setting for setting up PUCCH transmissionpower is described with reference to Equation 2.

In Equation 2, PO_PUCCH is an offset value given by a BS, and g(i) is avalue constantly adjusted by a TPC. In detail, P₀ _(_) _(PUCCH) includesP₀ _(_) _(NOMINAL) _(_) _(PUCCH) as a value reflecting a cell-commonenvironment and P_(O) _(_) _(UE) _(_) _(PUCCH) as a value reflecting anenvironment of each wireless device. g(i) is initialized to g(0)=0 whenP₀ _(_) _(PUCCH) is initially set or reset. When a random access processis performed, the sum of ΔP_(rampup) as a cumulative value adjusted inthe random access process and δ_(msg2) given in a random access responseis initialized to g(0)=ΔP_(rampup)+δ_(msg2).

P₀ _(_) _(PUCCH) to be applied to PUCCH transmission power for eachPUCCH cell may be configured as follows.

(1) Set P₀ _(_) _(PUCCH) for each PUCCH cell through RRC signaling

(2) Use the same P₀ _(_) _(PUCCH) configured for the PCell to anotherPUCCH cell

(3) Set an offset value per PUCCH cell for P₀ _(_) _(PUCCH) configuredfor the PCell through RRC signaling

(4) Use the same P₀ _(_) _(NOMINAL) _(_) _(PUCCH) configured for thePCell to another PUCCH cell and set P_(O) _(_) _(UE) _(_) _(PUCCH) perPUCCH cell through RRC signaling, which is useful when there issimilarity in coverage, frequency, and positional environment betweenthe PPCell and the PCell but it is intended to differentiate the PUCCHtransmission performance of the wireless device between the PCell andthe PPCell.

(5) Use the same P_(O) _(_) _(UE) _(_) _(PUCCH) configured for the PCellto another PUCCH cell and set P₀ _(_) _(NOMINAL) _(_) _(PUCCH) per PUCCHcell through RRC signaling, which is useful when there is difference incoverage, frequency, and positional environment between the PPCell andthe PCell but it is intended to manage the PUCCH transmissionperformance of the wireless device at a similar level between the PCelland the PPCell.

g(t) to be applied to PUCCH transmission power for each PUCCH cell maybe initialized as follows. When no random access process is performed ina corresponding PUCCH cell, g(0) may be set as follows.

(1) When new P0_PUCCH is set for the PUCCH cell or new P₀ _(_) _(PUCCH)is set for the PCell, set g(0)=0.

(2) Set g(0) to the sum of ΔP_(rampup) and δ_(msg2) adjusted in the lastrandom access process performed in the PCell. This may be applied whennew P₀ _(_) _(PUCCH) is not set for the PUCCH cell or new P₀ _(_)_(PUCCH) is not set for the PCell.

(3) Set whether to apply (1) or (2) through RRC signaling.

FIG. 6 is a block diagram illustrating a wireless communication systemaccording to one embodiment of the present invention.

A wireless device 50 includes a processor 51, a memory 52 and atransceiver 53. The memory 52 is connected to the processor 51, andstores various instructions implemented by the processor 51. Thetransceiver 53 is connected to the processor 51, and transmits and/orreceives radio signals. The processor 51 implements proposed functions,processes and/or methods. In the above embodiments, a UL controloperation of the wireless device may be implemented by the processor 51.When the above embodiments are implemented by a software instruction,the instruction may be stored in the memory 52 and may be executed bythe processor 51 to perform the above operation.

ABS 60 includes a processor 61, a memory 62 and a transceiver 63. The BS60 may operate in an unlicensed band. The memory 62 is connected to theprocessor 61, and stores various instructions implemented by theprocessor 61. The transceiver 63 is connected to the processor 61, andtransmits and/or receives radio signals. The processor 61 implementsproposed functions, processes and/or methods. In the above embodiments,an operation of the BS may be implemented by the processor 61.

The processor may include Application-Specific Integrated Circuits(ASICs), other chipsets, logic circuits, and/or data processors. Thememory may include Read-Only Memory (ROM), Random Access Memory (RAM),flash memory, memory cards, storage media and/or other storage devices.The RF unit may include a baseband circuit for processing a radiosignal. When the above-described embodiment is implemented in software,the above-described scheme may be implemented using a module (process orfunction) which performs the above function. The module may be stored inthe memory and executed by the processor. The memory may be disposed tothe processor internally or externally and connected to the processorusing a variety of well-known means.

In the above exemplary systems, although the methods have been describedon the basis of the flowcharts using a series of the steps or blocks,the present invention is not limited to the sequence of the steps, andsome of the steps may be performed at different sequences from theremaining steps or may be performed simultaneously with the remainingsteps. Furthermore, those skilled in the art will understand that thesteps shown in the flowcharts are not exclusive and may include othersteps or one or more steps of the flowcharts may be deleted withoutaffecting the scope of the present invention.

What is claimed is:
 1. A method for controlling uplink transmissionpower in a wireless communication system, the method performed by awireless device and the method comprising: receiving transmit powercommand (TPC) monitoring information to adjust an uplink transmissionpower for a first physical uplink control channel (PUCCH) cell and asecond PUCCH cell, the TPC monitoring information including a first TPCindex assigned to the first PUCCH cell and a second TPC index assignedto the second PUCCH cell; receiving a TPC payload by monitoring adownlink control channel based on the TPC monitoring information, theTPC payload including a plurality of TPCs; acquiring a first TPC for thefirst PUCCH cell and a second TPC for the second PUCCH cell from theplurality of TPCs based on the first TPC index and the second TPC index;and applying the first TPC and the second TPC to PUCCH transmissions onthe first PUCCH cell and the second PUCCH cell, wherein the wirelessdevice is configured with dual connectivity by being configured with afirst set of serving cells and a second set of serving cells, whereinthe first PUCCH cell is only one cell which is capable of receiving afirst PUCCH in the first set of serving cells, and wherein the secondPUCCH cell is only one cell which is capable of receiving a second PUCCHin the second set of serving cells.
 2. The method of claim 1, whereinthe TPC monitoring information comprises a TPC identifier masked with acyclic redundancy check (CRC) of the downlink control channel.
 3. Anapparatus for controlling uplink transmission power in a wirelesscommunication system, the apparatus comprising: a transceiver configuredto transmit and receive a radio signal; and a processor connected to thetransceiver and configured to: instruct the transceiver to receivetransmit power command (TPC) monitoring information to adjust an uplinktransmission power for a first physical uplink control channel (PUCCH)cell and a second PUCCH cell, the TPC monitoring information includingfirst TPC index assigned to the first PUCCH cell and a second TPC indexassigned to the second PUCCH cell, instruct the transceiver to receive aTPC payload by monitoring a downlink control channel based on the TPCmonitoring information, the TPC payload including plurality of TPCs,acquire a first TPC for the first PUCCH cell and a second TPC for thesecond PUCCH cell from the plurality of TPCs based on the first TPCindex and the second TPC index, and instruct the transceiver to applythe first TPC and the second TPC to PUCCH transmissions on the firstPUCCH cell and the second PUCCH, wherein the apparatus is configuredwith dual connectivity by being configured with a first set of servingcells and a second set of serving cells, wherein the first PUCCH cell isonly one cell which is capable of receiving a first PUCCH in the firstset of serving cells, and wherein the second PUCCH cell is only one cellwhich is capable of receiving a second PUCCH in the second set ofserving cells.
 4. The apparatus of claim 3, wherein the TPC monitoringinformation comprises a TPC identifier masked with a cyclic redundancycheck (CRC) of the downlink control channel.